Which of the following blood types may be referred to as the universal donor?

This is a bit of a trick question since there is no such thing as a universal donor. O negative lacks the A antigen (an antigen is something that the immune system may respond to), the B antigen, and the Rh factor. Hence, at one time the O- blood type was considered to be the universal donor.

Asked by Eugene Fenster · Last updated 4 weeks ago · 22.7K views